"The most mysterious architecture by the most mysterious of architects, nature's coliseum, Gavarnie…"
The Cirque de Gavarnie is a famous example of a cirque in the central Pyrenees, in the Pyrenees National Park. The cirque is 800 m wide (on the deepest point) and about 3000 m wide at the top. The Cirque de Gavarnie is placed about 4 km south of the village Gavarnie. From its floor, glacially eroded limestone rock walls rise to about 1500 m. It has three conspicuous terraces in which precipitous faces are succeeded upward by steep slopes of ice and snow. The Grande Cascade waterfall, one from the largest waterfalls in Europe, plunges about 425 m from the eastern side. Above the amphitheatre are the high mountain summits of the Franco-Spanish frontier ridge, rising to nearly 3 350 m (the Large peak of Astazou, the Peak of Marboré, the Peak of the Eastern cascade, the Turn of Gavarnie, the Helmet of Gavarnie and the Peak of Taillon). Also conspicuous is the deep cleft known as the Breche de Roland. Nearby is cave Grotte Casteret, containing a frozen underground stream. This magnificent piece of Nature has been recently recognized as UNESCO World Heritage site. The Cirque de Gavarnie is one of the most visited sites in the Pyrenees.
A cirque (French for "circus") is an amphitheatre-like valley, or valley head, formed at the head of a alpine glacier by erosion. A cirque is a landform found in the mountains as a result of alpine glaciers. They can be up to a square kilometers in size, situated high on a mountain side near the firn line, and are typically partially surrounded on three sides by steep cliffs. The highest cliff is often called a headwall. The fourth side is the "lip" which is the side that the glacier flowed away from the cirque. Many glacial cirques contain tarns dammed by either till or a bedrock threshold. When enough snow accumulates it can flow out the opening of the bowl and form valley glaciers which can be several kilometers long.
Cirques form in conditions which are favorable; which in the northern hemisphere includes the north-east slope where they are protected from the majority of the sun's energy and from the prevailing winds. These areas are sheltered from heat, encouraging the accumulation of snow; if the accumulation of snow increases, the snow turns into glacial ice. The process of nivation follows, whereby a hollow in a slope may be enlarged by freeze-thaw weathering and glacial erosion. The freeze-thaw erodes at the lower rocks and causes it to disintegrate, which can result in an avalanche bringing down more snow and rock to add to the growing glacier. Eventually, this hollow can become big enough so that glacial erosion intensifies. Debris (or till) in the ice may also abrade (glacial abrasion) the bed surface; should ice move down a slope it would have a "sandpaper effect" on the bedrock beneath on which it scrapes.
Additional information you can find on info-board at N42° 42.242' W0° 00.482'.
For the valid "cache found" log:
1) you have to upload a photo of you with GPS close to the cache coordinates
2) and send me via e-mail answers to these five questions:
- when were deposited here sediments creates Cirque (approx.; in millions years B.C.) ?
- when was the cirque created (approx.; in thousands years B.C.) ?
- what is the name of famous French 19th century writer - author of the first sentence in the listing ?
- what is the name of the small bridge at coordinates N42° 42.161' W0° 00.399' ?
- what is the main mineral which creates Cirque ?